Method and apparatus for melting, purifying and alloying metals

ABSTRACT

An arrangement in which metallic particles lie on a movable support. The particles have directed onto them an electron beam. While the support executes oscillating motion, the metallic particles retain their position in space at a stationary location. The motion of the support results in rolling of the metal particles. The particles are in molten state and retain their shape through their surface tension characteristics.

United States Patent [191 Aichert METHOD AND APPARATUS FOR MELTING,PURIFYING AND ALLOYING METALS [76] lnventor: Hans Aichert,Westbahnhofstrasse 15, 6450 Hanau am Main, Germany [22] Filed: June 13,1973 [21] Appl. No.: 369,434

[30] Foreign Application Priority Data June 20, I972 Germany 233l770[52,] US. Cl 266/34 V; 13/31; 75/49; 75/10 V; 266/33 R [51] Int. Cl.C216 7/10 [58] Field of Search 13/31; 75/10 R, 10 V, 49, 75/65 EB;266/34 R, 34 V, 39, 33 R, 33 S [56] References Cited UNITED STATESPATENTS 1,497,696 6/1924 Pulliam 266/34 R Apr. 22, 1975 l/l970 Chcngl3/3l X 2/l97l Smith 266/34 V Primary Examiner-Gerald A. Dost Attorney,Agent, or Firm-Joseph F. Padlon ABSTRACT An arrangement in whichmetallic particles lie on a movable support. The particles have directedonto them an electron beam. While the support executes oscillatingmotion, the metallic particles retain their position in space at astationary location. The motion of the support results in rolling of themetal particles. The particles are in molten state and retain theirshape through their surface tension characteristics.

3 Claims, 2 Drawing Figures METHOD AND APPARATUS FOR MELTING, PURIFYINGAND ALLOYING METALS BACKGROUND OF THE INVENTION The present inventionrelates to an arrangement for melting, purifying, as well as alloyingmetallic elements which are in molten state and retain their shapethrough their surface tension. The metallic elements are present in avacuum on a support which has applied to it a source of energy for thepurpose of displacing the support.

A process is known in the art of the preceding species in which anenergy source in the form of an electron beam is used for melting themetallic elements, and

crucible-shaped container means is used for retaining the moltenmaterial. This molten material or metallic elements roll into balls ordroplets as a result of their surface tension. The support for themetallic molten balls or droplets is movable. At the same time, however,there is no relative motion between the metallic elements and thesupport when the latter is displaced. The molten material or elementsretain essentially their position relative to the support.

With the preceding process known in the art, it is not possible to treatthe metallic elements for purification purposes, in an effective manner,by a degassing process. The reason for this is that the support screensoff the lower portion of the molten material against an interchange ofgas with the surrounding environment. Thus, the required gas interchangeis only possible through the upper portion of the surface of the moltenmaterial. As a result, the oppositely-lying volume elements of themolten material encounter considerable diffusion path lengths. Theconsequence of this effect is that long processing time intervals areincurred which cannot be tolerated in practice. Furthermore, alloying ofthe materials with other substances in which thorough intermixing of theindividual components is achieved, is not at all possible with theconventionally known process.

A conventional process also known in the art uses a support in the formof symmetrical rotational crucible which is driven at uniform rotationalvelocity about an inclined axis. Through such an arrangement, however,it is not possible to obtain optimum purification and alloying ofmaterials within a reasonable time interval, since thorough intermixingdoes not take place.

Accordingly, it is an object of the present invention to provide anarrangement for purifying metals, as well as forming alloys of metals.

Another object of the present invention is to provide the aforementionedarrangement in which the metals remain continuously under the influenceof a source of energy for melting the metals while undergoingpurifcation or alloying.

A still further object of the present invention is to provide anarrangement, as described, in which quanti ties of molten metals arepurified and/or alloyed while they are not moved out of the path of asource of energy used for melting the materials.

Still another object of the present invention is to provide anarrangement which is simple in design and may be readily constructed inan economical manner.

SUMMARY OF THE INVENTION The objects of the present inventionareachieved by providing an arrangement in which the support for the moltenmetallic materials is moved or displaced so that the metallic elementsin molten state roll on the support while the latter is displaced. Suchrolling action executed by the metallic elements causes them to retaintheir positions in space. Furthermore, in view of the rolling action ofthe metallic elements, it is possible to continuously bring new surfaceportions of the metallic elements in contact with the surroundingatmosphere. The metallic elements are held together or retain theirshape as a result of their surface tension characteristics. By rollingon the support in this'manner, the metallic balls or droplets havesurface portions removed for predetermined time intervals from being incontact with the support. At the same time, the rolling action of thedroplets or metallic balls produces simultaneously a mixing processthrough which the individual metallic components or elements arethoroughly intermixed. Thus, through the rolling action, new volumeelements are continuously brought from the region at the surface of thedroplets or metallic balls and moved towards the interior thereof. Thenecessary length of the diffusion path is, hereby, strongly reduced, sothat the gas interchange or purification time is significantlyshortened. With the rolling and mixing actions the further advantage isrealized whereby small quantities of materials may be economicallyalloyed. Finally, the temperature distribution within the metallicelements is made more optimum as a result of the intermixing processes,so that local overheating is avoided with the accompanying vaporizationof alloying elements having low boiling points. Since the metallicelements retain their positions in space, it is not necessary to providecomplex regulating and control mechanisms which are usually required formoving the source of energy for heating the metallic elements so thatthe energy source may follow along with the motion of the metallicelements.

The process in accordance with the present invention may be carried outeither in vacuum or in the environment of a protective gas. Forreinforcing the purification effects, it is desirable to carry out theprocess under vacuum. Sources of energy used for melting the metallicelements may be in the form of electric arcs plasma beams or similarsuch means. Electron beams, however, have been found to be particularlyadvantageous. When using electron beams, it is essential to carry outthe process under vacuum, since widening of the electron beams withinsubstantially dense gases results in process difficulties which may evenmake it impossible to carry out the process. Electron beams,furthermore, possess the characteristic of high energy density, and theelectron beams may be easily deflected or controlled so as to bedirected onto a predetermined or desired target point or impact point.

The rolling motion of the metallic elements on the support may takeplace in any desired manner. However, it is particularly advantageouswhen the support executes a periodic oscillation. An arrangement forcarrying out the process in accordance with the present invention, has avacuum chamber, a source of energy and a support for treating orprocessing the metallic elements. In accordance with the presentinvention, the support is rotatably suspended and possesses acircularshaped surface on which the metallic elements may roll. Theplace through the circle of the rolling surface is vertical, and thepoint of rotation for the displace ment or motion coincides with thecenter point of the rolling surface. The support, furthermore, can alsobe in the form of a ring-shaped closed groove having a horizontal axis.Upon rotation of the support about this axis, the molten metallicelements retain their position at the lowest point or location on thegroove which is also below the axis of rotation. Upon applying aperiodic oscillation to the support, it is sufficient to use a sectionfrom this ring-shaped crucible, and to secure this section about thecenter point. For this purpose, the support is advantageously secured toa rocker arm having a horizontal axis of rotation which passes throughthe center point of the circular plane of the rolling surface.

As a result of the periodic oscillating motion or displacement, improvedpuification and alloying effects are attained, since the intermixingprocess is significantly intensified. Molten particles from the interiorof the metallic elements are brought to the surface of the elements withgreater assurance, so that a gas interchange may take place with thesurrounding atmosphere or environment. The charging and removal of themetallic elements from the arrangement is also simplified, since it isonly necessary to simply tip the return point of the oscillatingdisplacement about the oscillating axis.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERREDEMBODIMENTS U Referring to the drawing and in particular to FIG. 1,anelectron beam generator 1 emits a high energy electron beam 3 in fullyaccelerated form through a pres-' sure step path 2. Through a magneticdeflection system, not shown in the drawing, the electron beam isdirected along a slightly curved path, and terminates at the end of thepath on a metallic element 4. As shown in the drawing, this metallicelement 4 is in the molten state and is held together to retain itsshape by its surface tension. The surface tension causes the element 4to assume the shape of a droplet, for example. The point of impact ofthe electron beam 3 may also be denoted as the focussed spot 5.

The metallic element 4 rests on a support 6 which is in the form of anarc-shaped groove 7. In particular the groove 7 has a circular shape,and the plane of the cir- 'cle lies in the plane of the drawing which,at the same time is vertical in practice. The arc-shaped groove 7 is asegmentof a circular-shaped ring crucible having a hollow chamber 8 forretaining a cooling medium as,

' in the direction perpendicular to the plane of the drawfor example,water. The support is, furthermore, bent ing, so that a hammock-shapedtrough or tub results. This trough or tub encloses the molten metallicelement 4 under maintenance of a stable balanced state. The center pointof the circle is denoted by 9. This center point 9 serves simultaneouslyas the axis of rotation or oscillation of the support 6 and a rockerarm10 is pivoted about this axis 9. In conjunction with a drive,

not shown in the drawing, the support 6 is to be periodically oscillatedor displaced so 'that end positions 6a and 6b shown in dotted formresult. The frequency of oscillation for displacing the support liespreferably within the range of 0.1 and 1 Hz. The amplitude ofoscillation in this embodiment is substantially 60. By carrying out thisoscillating motion. the metallic element 4 executes a rolling motion onthe inner surface of the support 6. This inner surface is denoted as therolling surface I! in the drawing. As a result of the rolling of themetallic element, new parts are brought to the upper surface from therolling surface 11, so that they are continuously subjected to contactwith the surrounding atmosphere. Since the lowest point of the support 6remains at the same position as a result of the geometrical design, themetallic element 4 is forced to remain also in the position shown in thedrawing, which is below the axis of rotation 9. With this arrangementthe electron beam 3 will continuously be directed onto the metallicelement 4. The entire arrangement, furthermore, is surrounded by avacuum chamber la, which is evacuated by means of vacuum pumps, also notshown in the conventional manner.

In FIG. 2, parts which are identical to those used in FIG. 1 are denotedby the same reference numerals. In place of the electron beam generator1, however, an electric arc electrode 12 is provided. By applying avoltage between the electrode and the support 6 which is in electricalcontact with the metallic element 4, an are 13 may be generated betweenthe electrode and the metallic element 4. This electric are 13 may beused for melting and further heating of the metallic element 4. Asidefrom using an electric arc in FIG. 2, the remaining functions of thearrangement of FIG. 2 are similar to the embodiment of FIG. 1. In FIG.2, the oscillating motion or displacement is carried out perpendicularto the plane of the drawing.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofarrangements for melting, purifying and alloying materials, differingfrom the types described above.

While the invention has been illustrated and described as embodied inarrangements for melting, purifying and alloying materials, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

I claim:

1. An arrangement for processing metallic materials under vacuum,comprising, in combination, a movable support; a metallic substance onsaid support; means for applying heat to said metallic substance on saidsupport for maintaining said metallic substance in molten state, saidmetallic substance assuming a shape determined by the surface tensioncharacteristics of said metallic substance; means for rotatablysuspending said support about a predetermined pivot axis, said support2. The arrangement as defined in claim I wherein said means forrotatably suspending said support com prises a rocker arm suspended fromsaid pivot axis, said pivot axis being horizontal and passing throughthe center point of said rolling surface.

3. The arrangement as defined in claim I wherein said metallic substanceis in form of a droplet.

* I. l k

1. AN ARRANGEMENT FOR PROCESSING METALLIC MATERIALS UNDER VACUUM,COMPRISING, IN COMBINATION, A MOVABLE SUPPORT; A METALLIC SUBSTANCE ONSAID SUPPORT; MEANS FOR APPLYING HEAT A SAID METALLIC SUBSTANCE ON SAIDSUPPORT FOR MAINTAINING SAID METALLIC SUBSTANCE IN MOLTEN STATE, SAIDMETALLIC SUBSTANCE ASSUMING A SHAPE DETERMINED BY THE SURFACE TENSIONCHARACTERISTICS OF SAID METALLIC SUBSTANCE; MEANS FOR ROTATABLYSUSPENDING SAID SUPPORT ABOUT A PREDETERMINED PIVOT AXIS, SAID SUPPORTBEING A SEGMENT OF A CIRCULAT-SHAPED GROOVE AND HAVING A ROLLING SURFACEALONG WHICH SAID METALLIC SUBSTANCE ROLLS IN MOLTEN STATE RELATIVE TOSAID SUPPORT UPON DISPLACING SAID SUPPORT WITH PERIODIC OSCILLATINGMOITIONS AROUND THE PIVOT AXIS OF SAID SUPPORT, THE PLANE THROUGH THECIRCULAR-SHAPED SECTION OF SAID SUPPORT BEING VERTICAL, SAID PIVOT AXISCOINCIDING WITH THE CENTER OF SAID ROLLING SURFACE.
 1. An arrangementfor processing metallic materials under vacuum, comprising, incombination, a movable support; a metallic substance on said support;means for applying heat to said metallic substance on said support formaintaining said metallic substance in molten state, said metallicsubstance assuming a shape determined by the surface tensioncharacteristics of said metallic substance; means for rotatablysuspending said support about a predetermined pivot axis, said supportbeing a segment of a circular-shaped groove and having a rolling surfacealong which said metallic substance rolls in molten state relative tosaid support upon displacing said support with periodic oscillatingmotions around the pivot axis of said support, the plane through thecircular-shaped section of said support being vertical, said pivot axiscoinciding with the center point of said rolling surface.
 2. Thearrangement as defined in claim 1 wherein said means for rotatablysuspending said support comprises a rocker arm suspended from said pivotaxis, said pivot axis being horizontal and passing through the centerpoint of said rolling surface.